Distributed multiple-input multiple-output downlink configuration

ABSTRACT

Aspects of this disclosure relate to distributed multiple-input multiple-output (MIMO) downlink configuration. Features are described for a network controller (e.g., baseband unit) to receive one or more requests including a desired transmission mode and/or active set of serving nodes for wireless communication service(s) for user equipment. The baseband unit may determine an optimal configuration in consideration of the desired parameters along with other network information. The network controller may then transmit one or more configuration messages via the network to optimally allocate resources distributed within the network.

BACKGROUND Technical Field

Embodiments of this disclosure relate to wireless communication systemssuch as heterogeneous multiple-input multiple output wirelesscommunication systems.

Description of Related Technology

The types of modern computing devices continues to increase along withthe differing and dynamic needs of each device. The wirelesscommunication systems providing services to such devices are facingincreasing constraints on resources and demands for quality andquantities of service. Accordingly, improvements in providing wirelesscommunication services, such as in a multiple-input multiple-outputsystem, are desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating a heterogeneous multiple-inputmultiple-output (MIMO) network in which user equipment (UE) and anetwork system wirelessly communicate according to an embodiment.

FIG. 2 is a logical diagram illustrating which types of wirelesscommunications can be provided in which modes of operation inheterogeneous MIMO networks.

FIG. 3 is a diagram illustrating an example environment for coordinatedmultipoint communications for a UE.

FIG. 4 is a diagram illustrating an example environment including macrodiversity communications for a UE.

FIG. 5 is a schematic diagram illustrating a scheduler of a networksystem in a heterogeneous MIMO wireless network according to anembodiment.

FIG. 6 is a message flow diagram of an embodiment for configuringdownlink data transmission for a user equipment.

FIG. 7 is a message flow diagram of an embodiment for updating downlinkdata transmission configuration for a user equipment.

FIG. 8 is a block diagram illustrating network system that includes anexample base band unit according to an embodiment.

FIG. 9 is a flow diagram illustrating an example method of dynamicallyconfiguring downlink data traffic modes for a user equipment in anetwork.

FIG. 10 is a flow diagram illustrating an example method of dynamicallyconfiguring downlink data traffic modes for a user equipment in anetwork from the user equipment's perspective.

FIG. 11 is a diagram that illustrates representative communications andevents in a heterogeneous MIMO network associated with a user equipmentrequesting to receive downlink data in a desired mode according to anembodiment.

FIG. 12 is a schematic block diagram of an example UE according to anembodiment.

FIG. 13 is a flow diagram of an example process of requesting a selectedcommunication mode in which to receive data at an antenna of a UEaccording to an embodiment.

FIG. 14 is a flow diagram of an example process of controlling adownlink data transmission mode to a UE based on a request from the UEaccording to an embodiment.

FIG. 15 is a diagram illustrating allocation of active sets andtransmission modes in a heterogeneous MIMO environment.

FIG. 16A is a diagram illustrating an active set and transmission modeallocation in a heterogeneous MIMO environment.

FIG. 16B is a diagram illustrating an updated active set andtransmission mode allocation for the heterogeneous MIMO network of FIG.16A with updated network demands.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a network system that includes antennaelements and a scheduler in communication with the antenna elements. Thescheduler is configured to receive, via at least one antenna elementincluded in the antenna elements, channel state information for a userequipment. The channel state information identifies a quality of atransmission from one or more of the antenna elements to the userequipment. The scheduler is configured to determine a downlink datatransmission mode to the user equipment based at least in part on thechannel state information and additional network system information. Thescheduler is configured to cause transmission of active set data to theuser equipment. The active set data identifies one or more serving nodesto provide a wireless downlink transmission service to the userequipment in the downlink data transmission mode.

Another aspect of this disclosure is a method controlling a downlinkdata transmission mode for a user equipment. The method includesreceiving, via at least one antenna element included in the antennaelements, channel state information for a user equipment. The channelstate information identifies a quality of a transmission from one ormore of the antenna elements to the user equipment. The method includesdetermining a downlink data transmission mode to the user equipmentbased at least in part on the channel state information and additionalnetwork system information. The method also includes causingtransmission of active set data to the user equipment. The active setdata identifies one or more serving nodes to provide a wireless downlinktransmission service to the user equipment in the downlink datatransmission mode.

Another aspect of this disclosure is a network system for downlink datatransmission in multiple-modes. The network system includes a schedulerand a transmitter in communication with the scheduler. The scheduler isconfigured to schedule a first downlink data transmission to a userequipment in a coordinated multi-point mode and to schedule a seconddownlink data transmission to the user equipment in an alternativedownlink data mode. The transmitter is configured to output first dataassociated with the first downlink data transmission for transmission tothe user equipment in the coordinated multi-point mode and to outputsecond data associated with the second downlink data transmission fortransmission to the user equipment in the alternative downlink datamode.

Another aspect of this disclosure is a user equipment that includesantenna elements, a receiver configured to process a signal received bythe antenna elements, and a processor. The processor is configured toreceive, from the receiver, first active set data identifying one ormore serving nodes to provide downlink data transmission service to theuser equipment in a coordinated multipoint mode. The processor isconfigured to detect a characteristic of the user equipment. Thecharacteristic comprises at least one of: an application type to utilizethe downlink data transmission service, a protocol to utilize over thedownlink data transmission service, or a device type for the userequipment. The processor is configured to cause transmission, via atleast one of the antenna elements, of channel state information for theuser equipment and the characteristic. The channel state informationidentifies a quality of a transmission from a network system to the userequipment. The processor is configured to receive, from the receiver viaat least one of the antenna elements, updated active set dataidentifying one or more serving nodes to provide transmission service tothe user equipment in an alternate downlink data transmission mode. Thealternate downlink data transmission mode includes at least one ofsynchronized transmission across multiple network nodes for coherentcombining, transmissions across multiple network nodes for non-coherentcombining, or individual transmission from a selected best serving node.The processor is configured to cause the receiver to be adjusted forprocessing the signal in the alternative downlink data transmission modefrom the one or more serving nodes identified by the updated active setdata

Another aspect of this disclosure is a method of downlink transmissioncontrol for a user equipment. The method includes receiving, from areceiver of a user equipment, a first active set data identifying one ormore serving nodes to provide downlink data transmission service to theuser equipment in a coordinated multipoint mode. The method alsoincludes detecting a characteristic of the user equipment. Thecharacteristic comprises at least one of: an application type to utilizethe downlink data transmission service, a protocol to utilize over thedownlink data transmission service, or a device type for the userequipment. The method includes causing transmission, via at least one ofa plurality of antenna elements of channel state information for theuser equipment and the characteristic of the user equipment. The channelstate information identifies a quality of a transmission from a networksystem to the user equipment. The method further includes receiving,from the receiver via at least one of the antenna elements, updatedactive set data identifying one or more serving nodes to provide thedownlink data transmission service to the user equipment in an alternatedownlink data transmission mode. The alternate downlink datatransmission mode includes at least one of synchronized transmissionacross multiple network nodes for coherent combining, transmissionsacross multiple network nodes for non-coherent combining, or individualtransmission from a selected best serving node.

Another aspect of this disclosure is a user equipment that includesantenna elements and a processor. The antenna elements include a firstantenna element. The processor is configured to receive, from a basestation, information identifying an active set of one or more servingnodes to provide transmission service to the user equipment. Theprocessor is configured to determine a selected mode of wirelesslyreceiving data using the first antenna element. The selected mode iseither a coordinated multipoint mode or an alternate downlink datatransmission mode. The processor is configured to cause transmission,via at least one of the antenna elements, of a request to receive dataat the first antenna element in the selected mode.

Another aspect of this disclosure is a method of requesting a selectedcommunication mode. The method includes receiving, from a base stationand with a processor of a user equipment, an active set of one or moreserving nodes to provide transmission service to the user equipment. Themethod includes determining, using the processor of the user equipment,a selected mode of wirelessly receiving data using a first antennaelement of the user equipment. The selected mode is either a coordinatedmultipoint mode or an alternate downlink data transmission mode. Themethod also includes wirelessly transmitting a request to receive dataat the antenna element in the selected mode.

Another aspect of this disclosure is a network system that includesantenna elements and a scheduler in communication with the antennaelements. The scheduler is configured to receive, via at least oneantenna element included in the antenna elements, a request from a userequipment to wirelessly receive data in a particular mode, in which theparticular mode is either a coordinated multipoint mode or an alternatedownlink data transmission mode. The scheduler is configured todetermine a downlink data transmission mode to the user equipment andactive set data based on the request and additional network systeminformation. The active set data identifies one or more serving nodes toprovide a wireless downlink transmission service to the user equipmentvia the downlink data transmission mode. The scheduler is configured tocause transmission of active set data to the user equipment.

Yet another aspect of this disclosure is a method of determining andimplementing a downlink traffic mode to a user equipment. The methodincludes receiving, via at least one antenna element, a request from auser equipment to wirelessly receive data in a particular mode, in whichthe particular mode is either a coordinated multipoint mode or analternate downlink data transmission mode. The method includesdetermining a downlink data transmission mode for wirelesslytransmitting data to the user equipment and active set data based on therequest and additional network system information. The active set dataidentifies one or more serving nodes to provide a wireless downlinktransmission service to the user equipment via the downlink datatransmission mode. The method also includes transmitting active set datato the user equipment.

The present disclosure relates to U.S. patent application Ser. No.16/180,848, titled “COOPERATIVE MULTIPLE-INPUT MULTIPLE-OUTPUT DOWNLINKSCHEDULING,” U.S. patent application Ser. No. 16/180,799, titled“VARIABLE MULTIPLE-INPUT MULTIPLE-OUTPUT DOWNLINK USER EQUIPMENT,” U.S.patent application Ser. No. 16/180,869, titled “USER EQUIPMENT ASSISTEDMULTIPLE-INPUT MULTIPLE-OUTPUT DOWNLINK CONFIGURATION,” each filed oneven date herewith and the disclosures of each of which are herebyincorporated by reference in their entireties herein.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings. The headings provided herein are for convenience only and donot necessarily affect the scope or meaning of the claims.

A distributed coordinated multiple-input multiple-output (MIMO) networkthat is designed to provide high uniform data rates across the networkcan face a number of significant challenges. Such challenges can includeservicing devices in mobility and/or providing reliable data service inthe case of poor channel conditioning, such as when most of the devicesare clustered around a few antenna nodes. Technology disclosed hereincan enable high data rate and high reliability for devices acrossDoppler and different channel conditions in a distributed MIMO network,thereby extending the benefits of distributed MIMO to larger set ofdevices reliably across the network. Such a network can provide lowlatency and high throughput with low jitter. Efficient quality ofservice at high user density can also be achieved with such a network.Highly robust connections can enable mobile edge computing.

In addition, there can be challenges with scalability across a wide areanetwork and/or complexity of implementing a distributed MIMO network atscale. Technology disclosed herein can scale across a wide area networkwithout significantly adding to complexity at scale.

Aspects of this disclosure relate to a unified coordinated MIMO networkacross multiple transmit-receive points (TRPs) to serve devices indifferent channel conditions. Available network resources can bedynamically partitioned to be used between coordinated multi-point(CoMP) operation and an alternative downlink data transmission mode ofoperation (e.g., single-frequency network (SFN), non-coherent combining(soft handoff), best server selection SIMO (single-inputmultiple-output), best server selection single user MIMO (SU-MIMO), bestserver selection multi-user MIMO (MU-MIMO), etc.). Accordingly, aunified framework for operating in CoMP or the alternative downlink datatransmission mode of operation is provided. The network and UE (userequipment) can use a criterion based on a set of metrics to determinethe best operating regime to serve a given antenna and/or device fordownlink data transmission. The metrics can include a device mobilitystate, a Doppler estimate, a measure of the network-to-UE channel matrixcondition such as Eigen-value spread, a network congestion measure(e.g., network load), the like, or any suitable combination thereof. TheUEs in mobility or with an ill-conditioned channel matrix can operate inthe alternative downlink data transmission mode for reliability, whereasother UEs can be served with CoMP to increase and/or maximize overallsystem capacity.

The technology disclosed herein relates to a wireless communicationsystem with resources to operate in both CoMP mode and at least onealternative downlink data transmission mode. Moreover, the technologydescribed herein provides a mechanism that enables the network to selectthe best mode of operation from between CoMP mode and at least onealternative downlink data transmission mode. User equipment can requestto receive data in either CoMP mode or the alternative downlink datatransmission mode. The wireless systems disclosed herein can enablerobust, consistently high data rate, ultra-low latency wirelessconnection within a dense network. The wireless systems disclosed hereinare applicable to user equipment with a variety of mobility and/or linkconditions.

The network and UEs may collect a set of monitoring metrics, which caninclude one or more of a channel matrix condition for each UE viameasuring Eigen spread, UE mobility via Doppler estimation, network loadvia scheduling metrics, and measure of UE channel state information(CSI), or throughput over time. The channel state information mayidentify a quality of a transmission from one or more antenna elements(e.g., a MIMO antenna array) to the user equipment. The network can makea determination of the best downlink data transmission mode to aparticular UE based on the metrics. The network can serve a UE in CoMPmode when conditions are suitable for CoMP mode. However, the networkcan serve the UE in the alternative downlink data transmission mode inresponse to detecting a condition indicating that CoMP mode isundesirable. For example, for a UE with a Doppler estimation exceeding athreshold or the channel Eigen spread larger than another threshold, thenetwork can serve the UE in the alternative downlink data transmissionmode. As another example, if the network is overly congested in CoMPmode, UEs with less favorable channel conditions can be served in thealternative downlink data transmission mode.

Technology disclosed herein can use UE channel conditions tosignificantly improve the robustness of a coordinated MIMO network toensure reliability in serving the users in adverse channel conditionswhile achieving high data capacity across the network for low mobilityusers. The technology disclosed herein provides a comprehensiveconsideration of operation regimes and the flexibility to choose thebest one for a particular set of conditions.

Heterogeneous MIMO Network

FIG. 1 is a diagram illustrating a heterogeneous multiple-inputmultiple-output (MIMO) network in which user equipment (UE) and anetwork system wirelessly communicate according to an embodiment. Theheterogeneous MIMO network can implement a downlink coordinated jointtransmission and/or reception across distributed antennas in acoordinated multipoint (CoMP) mode. The heterogeneous MIMO network canalso implement a macro diversity mode for wirelessly communicatingbetween UEs and the network system. The network system can partitionsystem resources between the different modes of operation. For example,carriers in the frequency domain can be used to partition resourcesbetween the different modes of operation. Alternatively or additionally,time slots can be used to partition resources between the differentmodes of operation in the time domain.

The heterogeneous MIMO network provides a unified approach to serve lowmobility and high mobility UEs. In addition, the heterogeneous MIMOnetwork can implement robust processing to handle singularities. Theheterogeneous MIMO network an address diverse channel conditions toprovide spectrally efficient service. Network system spectral efficiencycan be increased by dynamic load balancing.

FIG. 1 shows an example environment for distributed MIMO wirelesscommunications. Various standards and protocols may be included in theenvironment 100 to wirelessly communicate data between a base stationand a wireless communication device. Some wireless devices maycommunicate using an orthogonal frequency-division multiplexing (OFDM)digital modulation scheme via a physical layer. OFDM standards andprotocols can include the third generation partnership project (3GPP)long term evolution (LTE), the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which may beknown as WiMAX (Worldwide interoperability for Microwave Access), andthe IEEE 802.11 standard, which may be known as Wi-Fi. In some systems,a radio access network (RAN) may include one or more base stationassociated with one or more evolved Node Bs (also commonly denoted asenhanced Node Bs, eNodeB s, or eNBs, gNBs, or any other suitable Node Bs(xNBs)). In other embodiments, radio network controllers (RNCs) may beprovided as the base stations. A base station provides a bridge betweenthe wireless network and a core network such as the Internet. The basestation may be included to facilitate exchange of data for the wirelesscommunication devices of the wireless network.

The wireless communication device may be referred to a user equipment(UE). The UE may be a device used by a user such as a smartphone, alaptop, a tablet computer, cellular telephone, a wearable computingdevice such as smart glasses or a smart watch or an ear piece, one ormore networked appliances (e.g., consumer networked appliances orindustrial plant equipment), an industrial robot with connectivity, or avehicle. In some implementations, the UE may include a sensor or othernetworked device configured to collect data and wirelessly provide thedata to a device (e.g., server) connected to a core network such as theInternet. Such devices may be referred to as Internet of Things devices(IoT devices). A downlink (DL) transmission generally refers to acommunication from the base transceiver station (BTS) or eNodeB to thewireless communication device, and an uplink (UL) transmission generallyrefers to a communication from the wireless communication device to theBTS.

FIG. 1 illustrates a cooperative, or cloud radio access network (C-RAN)environment 100. In the environment 100, the eNodeB functionality issubdivided between a base band unit (BBU) 110 and multiple remote radiounits (RRUs) (e.g., RRU 125, RRU 135, and RRU 145). An RRU may includemultiple antennas, and one or more of the antennas may serve as atransmit-receive point (TRP). The RRU and/or a TRP may be referred to asa serving node. The BBU 110 may be physically connected to the RRUs suchas via an optical fiber connection. The BBU 110 may provide operationaldetails to an RRU to control transmission and reception of signals fromthe RRU along with control data and payload data to transmit. The RRUmay provide data to the network received from UEs within a service areaassociated with the RRU. As shown in FIG. 1, the RRU 125 providesservice to devices with a service area 120. The RRU 135 provides serviceto devices within a service area 130. The RRU 145 provides service todevices within a service area 140. For example, wireless downlinktransmission service may be provided to the service area 140 tocommunicate date to one or more devices within the service area 140.

The RRUs may include multiple antennas to provide multiple in multipleout (MIMO) communications. For example, an RRU may be equipped withvarious numbers of transmit antennas (e.g., 1, 2, 4, 8, or more) thatcan be used simultaneously for transmission to one or more receivers,such as a user equipment (UE). Receiving devices may include more thanone receive antenna (e.g., 2, 4, etc.). The array of receive antennasmay be configured to simultaneously receive transmissions from the RRU.Each antenna included in an RRU may be individually configured totransmit and/or receive according to a specific time, frequency, power,and direction configuration. Similarly, each antenna included in a UEmay be individually configured to transmit or receive according to aspecific time, frequency, power, and direction configuration. Theconfiguration may be provided by the BBU 110. The directionconfiguration may be generated based on network estimate using channelreciprocity or determined based on feedback from UE via selection of abeamforming codebook index, or a hybrid of the two.

The service areas shown in FIG. 1 may provide communication services toa heterogeneous population of user equipment. For example, the servicearea 120 may include a cluster of UEs 160 such as a group of devicesassociated with users attending a large public event. A mobile userequipment 170 may move from the service area 130 to the service area140. Another example of a mobile user equipment is a vehicle 156 whichmay include a transceiver for wireless communications for real-timenavigation, on-board data services (e.g., streaming video or audio), orother data applications. The environment 100 may include semi-mobile orstationary devices such as robotic device 158 (e.g., robotic arm,autonomous drive unit, or other industrial or commercial robot), or atelevision 154 also configured for wireless communications.

A user equipment 152 may be located with an area with overlappingservice (e.g., the service area 120 and the service area 130). Eachdevice in the environment 100 may have different performance needs whichmay, in some instances, conflict with the needs of other devices.

FIG. 2 is a logical diagram illustrating which types of wirelesscommunications can be provided in which modes of operation inheterogeneous MIMO networks. Macro diversity communications may beallocated for messages related to acquiring service, requesting accessto the service, and control messages for the service. Data traffic maybe communicated using either macro diversity communication mode orcoordinated multipoint mode for data traffic. Accordingly, the macrodiversity mode is an alternative downlink data transmission mode. Thealternative downlink data mode can be the mode in which acquisition,access, and control communications are communicated. The macro diversitymode or the coordinated multipoint mode can be selected based on anysuitable criteria disclosed herein.

FIG. 3 is a diagram illustrating an example environment for coordinatedmultipoint communications for a UE. In the environment 300, the UE 152may receive downlink data traffic from the RRU 125 and the RRU 135 witheach RRU sending one or more spatial layers via respective TRPs includedin the RRU. Each spatial layer can correspond to a beam. The spatiallayers may be coordinated such as by using a weighted combination foreach layer to provide transmissions to a specific UE. Different sets ofweighted combinations can be provided for different UEs. Thetransmissions from the RRU 125 and the RRU 135 may be coordinated by thebase band unit 110. Coordination may include coordinating the timing oftransmissions and data included in transmissions for the UE 152. The RRU125 may use a first channel 310 to transmit data to the UE 152 while theRRU 135 may use a second channel 320 to transmit data to the UE 152where the first and second channel are the same for CoMP.

FIG. 4 is a diagram illustrating an example environment including macrodiversity communications for a UE. In the environment 400, a UE 410 mayreceive data traffic over a channel 420 from the RRU 125. The RRU 125may be selected by the BBU 110 as the best serving node for the UE 410.The evaluation may be based on signal strength, channel stateinformation (CSI) reports received from the UE 410, mobility of the UE410, spatial channel condition of a channel for the UE 410, or otherfactors of the environment 400 detectable by the BBU 110. In someimplementations, the UE 410 may request the serving node. The UE 410 mayidentify the RRU 125 based on signal strength, anticipated data to betransmitted to or from the UE 410, or a control message received fromthe BBU 110. Another example of a macro diversity communication mode isindividual network node transmissions from a selected node.

A further example of a macro diversity communication mode issynchronized transmissions across multiple RRU that are coherentlycombined by the UE 410. In this mode, each RRU may transmit downlinkdata traffic and the UE 410 may decode portions of differenttransmissions to assemble the data. The decoding may be based ontransmission information (e.g., coefficients) shared between thetransmitting RRU and the UE 410. Another example of a macro diversitycommunication mode is non-coherent combination of transmissions frommultiple RRUs. In non-coherent systems, the UE 410 may decode receivedtransmissions based on statistical information (e.g., coefficients)derived from received signal characteristics from one or more RRU's, notnecessarily time aligned, and combine the received data as part of thedemodulation process or combine post decode. In CoMP mode, differentTRPs transmit different spatial layers (e.g., different data) to one ormore UEs. In a macro diversity mode, the transmission may be sent fromeither one TRP or the same data across multiple TRPs.

Existing systems are configured to use one communication mode,system-wide, for the downlink data traffic. By using only one downlinkdata traffic mode, systems may provide suboptimal service to at leastsome of the devices served. For example, in cases where a service areaincludes a high density of UEs concentrated near one of the many RRUs inthe area, the beamforming and other transmission coordination needed toprovide a high quality service to all UEs in the dense area may cause asubstantial downgrade in the communication rate within a service areautilizing coordinated multipoint methods. Similarly, in cases where a UEis moving rapidly, CoMP methods may incur substantial overhead toprovide service to the moving UE.

To indicate the downlink data traffic mode, the BBU 110 may communicateone or more identifiers to a UE. The identifiers indicate the RRUsproviding downlink data traffic to the UE. The set of identifiers may bereferred to as an active set for the UE. In a macro diversity mode, theactive set may include the identifier of a single RRU or a group of RRUstransmitting the same data to the UE for soft-combining (SFN) ornon-coherent combining (soft handoff). In a coordinated multipoint mode,the active set may include the identifiers of the RRUs coordinating toprovide one or more spatial layers of downlink data traffic to the UE.

As described in further detail below, the BBU 110 may dynamically assesscharacteristics of the network or the UE to determine which mode to usefor downlink data traffic for a UE. This allows the BBU 110 toselectively communicate with UEs based on network conditions oroperational needs of the UE. This also allows the BBU 110 to allocatetransmission resources in consideration of overall network impact ratherthan treating each UE as an independent assignment that has no impact onthe traffic mode assigned for other devices.

The environment 100 shown in FIG. 1 may represent a portion of a largerenvironment including additional or alternative base band units coupledwith additional or alternative remote radio units.

Mode Determination

A downlink data transmission mode can be dynamically determined in aheterogeneous MIMO network. As discussed above, the downlink datatransmission mode can be either a CoMP mode or an alternative downlinkdata transmission mode. The alternative downlink data transmission modecan be any of the macro diversity modes disclosed herein. Thealternative downlink data transmission mode can be the mode in whichacquisition, access, and control communications are communicated. Anetwork scheduler can determine the downlink data transmission mode froma base station to a UE and/or to one or more particular antennas of aUE. The downlink data transmission mode can be selected based on anetwork centric determination or a UE assisted determination. Thenetwork centric determination can be based on a UE report and systemload data. The UE assisted determination can be based on a request toreceive downlink transmission data in a selected mode by a UE. Moredetails regarding technical features of network centric modedetermination and UE assisted mode determination are provided herein.

The desired mode of operation can be selected by a scheduler based onany suitable information. One or more of the following types ofinformation can be used in determining a downlink data transmissionmode: UE link quality, UE mobility data, a network to UE channel matrixcondition, or network loading. Mobility data, such as Doppler estimationand/or channel state information (CSI) variation, can be used indetermining the desired mode. With more mobility, CoMP mode can be moredifficult and/or less effective. For instance, when a mobile phone isbeing used on a fast moving train, CoMP can be difficult due to poorchannel estimates as a result of, for example, the fast changing channelconditions and an alternative downlink data transmission mode can beselected. A network to UE channel matrix condition, such as a CSIestimation, can be used in determining the desired mode. The alternativedownlink data transmission mode can be used when a network to UE channelmatrix is undesirable and/or unsuitable for CoMP. Network loading datacan be used to generate interference data in a base station. Suchnetwork loading data can be used by a scheduler to determine theselected mode of operation. As an example, a scheduler can select thealternative downlink data transmission mode in response to the networkdata indicating a relatively high load on CoMP resources.

The scheduler can select a mode of downlink data transmission from oneor more serving nodes to a user equipment. The network scheduler canselect CoMP as the selected mode in response to determining thatconditions are suitable for CoMP. Otherwise, the network scheduler canselect the alternative downlink data transmission mode as the desiredmode.

The scheduler can select CoMP as the selected mode in response todetermining that mobility is less than a threshold. The mobility can bedetermined by a mobility measure of a UE, such as CSI or a Dopplerestimate. Alternatively or additionally, the scheduler can select CoMPas the selected mode in response to determining that the differencebetween maximum and mean Eigen-values of a downlink channel matrix isless than a threshold. For example, the scheduler can select CoMP as theselected mode in response to determining that (1) mobility is less thana first threshold, (2) the difference between maximum and meanEigen-values of a downlink channel matrix are less than a secondthreshold, (3) an estimated relative spectral efficiency for servingCoMP mode to the UE is higher than for the alternative downlink datatransmission mode, or (4) any suitable combination of (1) to (3). Forexample, the CoMP mode can be selected by (1), (2) and (3). As anotherexample, CoMP mode can be selected by any two of (1), (2), or (3). Insome instances, CoMP mode can be selected by any one of (1), (2), or(3). The first threshold and/or the second threshold can be adjustablebased on one or more characteristics associated with a UE. The one ormore characteristics of the UE can include a device type, a softwareprogram running on a UE, a protocol, a use case, the like, or anysuitable combination thereof.

The scheduler can select the alternative downlink data transmission modeas the selected mode in response to determining that a conditionindicates that CoMP mode is undesirable. Such a condition can includeone or more of mobility being sufficiently high, a relatively low Eigenspread of a downlink channel matrix for a UE, or a sufficiently highload is detected on CoMP resources. Accordingly, the scheduler canselect the alternative downlink data transmission mode as the selectedmode in response to determining that (1) mobility is sufficiently highor (2) there is a relatively low Eigen spread of a downlink channelmatrix for a UE or (3) there is a sufficiently high load is detected onCoMP resources or (4) an estimated relative spectral efficiency forserving the alternative downlink data mode to the UE is higher than forthe CoMP mode. Mobility can be sufficiently high when mobility exceedsthe first threshold. The load on CoMP resources can be based ondetecting interference and/or a relatively large number of UEs inproximity to each other. A sufficiently high load on CoMP resources caninvolve the number of UEs being significantly greater than the number ofdistributed antennas of a heterogeneous MIMO network.

The scheduler may be implemented as a discrete hardware device. Thescheduler may include one or more communication ports to transmit and/orreceive messages via a network. For example, the scheduler may becommunicatively coupled with a BBU to provide at least a portion of thescheduling features described. In some implementations, the schedulermay be integrated within a BBU. The scheduler may be implemented usingspecifically configured circuitry to provide at least a portion of thescheduling features described. In some implementations, the schedulermay include a processor configured by specific instructions stored in anon-transitory data store. When the processor executes the specificinstructions, it may cause the scheduler to perform at least a portionof the scheduling features described.

FIG. 5 is a schematic diagram illustrating a heterogeneous MIMO wirelessnetwork 500 that includes a baseband unit 510 according to anembodiment. As illustrated, the baseband unit 510 includes a user dataqueue block 512, a scheduler control 514, a time/frequency resourceallocation block 516, an active set and beam management block 518, atransceiver 520, a CSI computation block 522, and an active set servingnode update block 524. The baseband unit 510 can include any suitablephysical hardware to implement the illustrated blocks. For example, thebaseband unit 510 can include a processor and computer readable storageto implement any suitable blocks shown in FIG. 5. The heterogeneous MIMOwireless network 500 also includes user equipment 560 and 565 andserving nodes 570, 580, and 590.

The baseband unit 510 includes a scheduler that schedules user data forwireless transmission from serving nodes 570, 580, and 590 to userequipment 560 and 565. The scheduler can schedule downlink data trafficin both the CoMP mode and the alternative downlink data transmissionmode. For example, the scheduler can schedule downlink data traffic toone UE in the CoMP mode and to another UE in the alternative downlinkdata. As another example, the scheduler can schedule downlink datatraffic to a UE in the CoMP mode at a first time and to the UE in thealternative downlink data at a second time. The serving nodes canalternatively be referred to as transmission points for downlink datatransmission. The scheduler can schedule data from any suitable numberof serving nodes to any suitable number of user equipment. The schedulercan include the user data queue block 512, the scheduler control 514,the time/frequency resource allocation block 516, the active set andbeam management block 518, the CSI computation block 522, and the activeset serving node update block 524.

The transceiver 520 can provide a UE report from the user equipment 560and/or 565 to the scheduler. The UE report can include CSI informationand active set information. The UE report can also include any othersuitable information from a UE, such as other information from which todetermine a selected mode of downlink data transmission. The CSIcomputation block 522 can compute CSI data from data in the UE report.The active set serving node update block 524 can determine an updatedactive set for one or more UEs. In some instances, the active setserving node update block 524 can determine an updated active set for asubset of one or more antennas of a UE. The active set serving nodeupdate block 524 can use any suitable metrics disclosed herein todetermine a selected downlink data transmission mode and update anactive set associated with a UE.

The updated active set data is provided to the scheduler control 514.The user data queue block 512 can provide user data to the schedulercontrol 514. The schedule control 514 provides user data to thetransceiver 520 and also provides instructions to the time/frequencyresource allocation block 516. The time/frequency resource allocationblock 516 can schedule timing and frequency of downlink datatransmission from serving nodes 570, 580, and 590. This can avoid timingconflicts and conflicts in the frequency domain. The active set and beammanagement block 518 can identify serving nodes 570, 580, and 590 forproviding wireless transmission services to UEs 560 and 565 from activeset data. The active set and beam management block 518 can groupdownlink data transmissions and manage beamforming from the servingnodes 570, 580, and 590 to UEs 560 and 565. The transceiver 520 providesdata for transmission by the serving nodes 570, 580, and 590 to UEs 560and 565.

As shown in FIG. 5, the scheduler can cause a network system of theheterogeneous MIMO wireless network 500 to wirelessly transmit firstuser data to a first user equipment 565 in CoMP mode and to wirelesslytransmit second user data to a second user equipment 560 in analternative downlink data transmission mode. Moreover, the scheduler cancause a network system of the heterogeneous MIMO wireless network towirelessly transmit user data to any suitable number of UEs in CoMP modeand any suitable number of UEs in the alternative downlink datatransmission mode.

Network Centric Communication Mode Determination

FIG. 6 is a message flow diagram of an embodiment for configuringdownlink data transmission for a user equipment. The message flow 600illustrates example messages that may be transmitted between a userequipment 610, a remote radio unit 620, and a base band unit 630.Additional or alternative entities may be include to mediate one or moreof the interactions shown such as network routers, switches, securitydevices, or the like.

Via message 650, the UE 610 may request network services via the RRU620. The connection request may include an identifier for the UE 610such as a MEID or UUID of the UE 610. In some implementations, theidentifier may be associated with account information indicating servicelevels and other network services accessible by the UE 610. The message650 may be received via a wireless communication channel connecting theUE 610 with the RRU 620.

Via message 652, the RRU 620 may request connection for the UE 610 fromthe BBU 630. The request may include the identifier for the UE 610 alongwith an identifier of the RRU 620 receiving the connection request fromthe UE 610. The message 652 may be transmitted from the RRU 620 to theBBU 630 using a wired or a wireless communication channel.

Via message 654, the BBU 630 may generate an active set of one or moreserving nodes (e.g., RRUs or TRPs) to provide the requested service tothe UE 610. The generation of the active set may include generatingscheduling information for the UE 610. The scheduling information mayidentify one or more of transmission mode, time, frequency, power,beamforming matrix, tone allocation, or channel rank for downlink datatransmissions to the UE 610. The generation of the active set mayinclude consideration of network system information such as a networkload. For example, if the number of UEs serviced by the RRU 620 exceedsa threshold, it may be desirable to assign an active set representing amacro diversity transmission mode.

Via message 656, the BBU 630 may transmit the downlink schedulingparameters to the RRU 620. The parameters may include transmission mode,time, frequency, power, beamforming matrix, tone allocation, or channelrank. The RRU 620 may transmit a message 658 to the UE 610 indicatingthe active set for the requested downlink transmission service. Themessage 658 may include transmission parameters the UE 610 may expectfrom the active set (e.g., transmission mode, time, frequency, power,beamforming matrix, tone allocation or rank).

The UE 610 may, via message 660, adjust a transceiver or other signalprocessing circuitry based on the parameters received via message 658.The adjustment may include tuning one or more antennas of the UE 610.The adjustment may include changing demodulation and/or decodingpipeline for the UE 610 to properly interpret downlink messages. Forexample, if the UE 610 is initially assigned a CoMP mode, subsequentconditions may cause the BBU 630 to change the UE 610 to a macrodiversity mode. The manner in which received messages are processed(e.g., decoded) may require a change in the demodulation and/or decodingpipeline or other element of the UE 610 to ensure continuity of a datatransaction as the mode changes.

Via message 662, the RRU 620 may adjust a transceiver or other signalprocessing circuitry based on the downlink scheduling parametersreceived via message 656. The adjustment of the RRU 620 may occurconcurrently or at an overlapping time with the adjustment of the UE610.

Having configured both the RRU 620 and the UE 610 for the downlink datatransmission mode identified by the BBU 630, messaging 664 may carrydata between the UE 610 and the RRU 620. Other RRUs (not shown) may beconfigured by the BBU 630 to provide downlink data transmissionservices. For example, if the downlink transmission mode is acoordinated multipoint mode, the RRU 620 and at least one additional RRUmay be configured to transmit data to the UE 610. The uplink anddownlink data transmissions can be in different modes. Alternatively oradditionally, the uplink and downlink data transmissions can havedifferent associated active sets. For instance, there can be a downlinkactive set and an uplink active set.

The messaging in FIG. 6 illustrates how an initial active set andnetwork tuning parameters for a first transmission mode may beidentified for a UE. As discussed, today's networks are dynamicecosystems with devices moving, powering on, powering off, and such.These dynamic conditions may cause an initial assessment of a downlinktransmission mode to change based on changing network and/or UEcharacteristics.

FIG. 7 is a message flow diagram of an embodiment for updating downlinkdata transmission configuration for a user equipment. The message flow700 illustrates example messages that may be transmitted between a userequipment 710, a remote radio unit 720, and a base band unit 730.Additional or alternative entities may be include to mediate one or moreof the interactions shown such as network routers, switches, securitydevices, or the like.

Via message 750, the UE 710 may detect UE conditions. The UE conditionsthat may be detected include channel conditions of the connection withthe RRU 720. Channel conditions may include signal strength,signal-to-noise ratio, spatial characteristics, Doppler information, UEcapability changes such as active receive and/or transmit antennas. TheUE conditions may include an operational characteristic of the UE 710such as the application(s) executing on the UE 710, communicationprotocols used by the application(s) executing on the UE 710, or motionof the UE 710 (e.g., Doppler estimation or channel state variation). TheUE conditions may include information about the UE 710 such as devicetype, operating system, peripheral devices attached to the UE 710, orthe like.

Via message 752, the UE 710 may provide at least a portion of the UEconditions detected via message 750 to the RRU 720. The message 752 mayinclude a channel state information (CSI) report. In someimplementations, the message 752 may include multiple messages, eachmessage including different UE conditions.

Via message 754, the RRU 720 may transmit the condition information tothe BBU 730. The message 754 may include identifiers for the UE 710 andthe RRU 720 to allow the BBU 730 to associate the condition informationwith a specific downlink channel (e.g., UE and RRU combination).

Based at least in part on the UE condition information along withnetwork condition information that may be detected by the BBU 730, viamessage 756, the BBU 730 may generate a downlink schedule for the UE710. The generation via message 756 may be similar to the generation viamessage 654 shown in FIG. 6. However, in FIG. 7 the UE 710 may alreadyhave an initial active set and transmission mode identified. Thisinitial active set and/or transmission mode may be changed due tochanges in network conditions or UE condition information.

The BBU 730 may provide downlink scheduling parameters to the RRU 720.The parameters may include one or more of transmission mode, time,frequency, power, beamforming matrix, tone allocation, or channel rank.The RRU 720 may transmit a message 760 to the UE 710 indicating theactive set and/or scheduling parameters for the requested downlinktransmission service. The message 760 may include transmissionparameters the UE 710 may expect from the active set (e.g., transmissionmode, time, frequency, power, beamforming matrix, tone allocation, orchannel rank). The message 760 may include an indication of thetransmission mode identified for the UE 710.

The UE 710 may, via message 762, adjust a transceiver, a receiver (e.g.,a receiver of a transceiver), or other signal processing circuitry basedon the parameters received via message 760. The adjustment may includetuning one or more antennas of the UE 710. The adjustment may includechanging demodulation and/or decoding pipeline for the UE 710 toproperly interpret downlink messages. For example, if the UE 710 isinitially assigned a CoMP mode, subsequent conditions may cause the BBU730 to change the UE 610 to a macro diversity mode. The manner in whichreceived messages are processed (e.g., decoded) may require a change inthe demodulation and/or decoding pipeline or other element of the UE 710to ensure continuity of a data transaction as the mode changes.

Via message 764, the RRU 720 may adjust a transceiver or other signalprocessing circuitry based on the downlink scheduling parametersreceived via message 758. The adjustment of the RRU 720 may occurconcurrently or at an overlapping time with the adjustment of the UE710.

Having configured both the RRU 720 and the UE 710 for the downlink datatransmission mode identified by the BBU 730, messaging 766 may carrydata between the UE 710 and the RRU 720. Other RRUs (not shown) may beconfigured by the BBU 730 to provide downlink data transmissionservices. For example, if the downlink transmission mode is acoordinated multipoint mode, the RRU 720 and at least one additional RRUmay be configured to transmit data to the UE 710.

FIG. 8 is a block diagram illustrating an example base band unit andremote radio unit according to an embodiment. The base band unit 820 maybe coupled with at least one remote radio unit 890. The remote radiounit 890 may include at least a first antenna 896 and a second antenna898 for MIMO wireless communications. Any antenna disclosed herein, suchas the antenna 896 or the antenna 898, can be referred to as antennaelement. The first antenna 896 and the second antenna 898 may be coupledwith a radio frequency (RF) front end 894. The RF front end 894 mayprocess signals received via the first antenna 896 and the secondantenna 898. Part of processing a signal may include transmitting thesignal to a transceiver 820 included in the BBU 802.

A processor 805 may receive signals received by the transceiver 820. Theprocessor 805 may be configured to determine a type of the signal. Forexample, if the signal includes a request for connection services, theprocessor 805 may provide the signal to an active set selector 835. Theactive set selector 835 may be configured to identify an active set ofserving nodes to provide the requested downlink data transmissionservice. The active set selector 835 can identify the active set for aUE based on information associated with the UE. Alternatively oradditionally, the active set selector 835 can identify the active setfor a UE based on information associated with one or more other UEs. Insome instances, the active set selector 835 can determine a transmissionmode for the downlink data transmission service. The BBU 802 may includea network monitor 825 to detect characteristics of the network such asthe number of UEs server by each RRU, network data transmission load, orthe like. The active set selector 835 may receive the networkcharacteristics from the network monitor 825 as a factor considered whenidentifying an active set and/or transmission mode for a UE request. Abeamformer 815 may be included in the BBU 802 to further identifyparameters for the serving nodes (e.g., RRUs) included in an active set.The parameters may include one or more of transmission mode, time,frequency, power, beamforming matrix, tone allocation, or channel rank.The beamformer 815 may determine optimal parameters for RRUs coupledwith the BBU 802 that facilitate a network-wide optimization of downlinkdata transmissions. In some implementations, a UE may provide arequested active set. The BBU 802 may include an active set arbitrator830 to reconcile a requested active set with an active set selected bythe active set selector 835. The active set arbitrator 830 may compare arequested set of serving nodes to the serving nodes identified by theactive set selector 835. The comparison may include ordering the servingnodes according to the UE recommendation. In some implementations, theactive set arbitrator 830 may provide a message to the UE indicatingconfirmation or other assessment for a requested active set. Forexample, if the UE requested nodes A and B but the BBU 802 identifiedonly B in the active set, the message may include a code indicating apartial match for the active set. Other status codes may be included tofacilitate efficient communication and assessment of requested activesets. The active set arbitrator 830 may additionally or alternativelycompare a requested transmission mode to the transmission modeidentified by the active set selector 835 or other element of the BBU802.

The BBU 802 may include a data store 810. The data store 810 may includeinstructions that can be executed by the processor 805 to implement thefeatures described. In some implementations, the data store 810 mayretain active sets or other scheduling information assigned to UEsserved by the BBU 802. The data store 810 may be indexed by UEidentifier and/or RRU identifier. This can expedite identification ofpreviously communicated scheduling information for the UE and formonitoring network conditions (e.g., number of UEs allocated to an RRUor antenna element of an RRU).

In addition to providing the scheduling information to the UE, thescheduling information may be used to configure the RRU 890. Theconfiguration may include adjusting the first antenna 896 such as byfrequency modulation, time modulation, altering transmission power froma power source 892, or adjusting direction, tone allocation, orbeamforming of the transmission.

FIG. 9 is a flow diagram illustrating an example method of dynamicallyconfiguring downlink data traffic modes for a user equipment in anetwork. The method 900 may be performed in whole or in part undercontrol of a coordination device such as a base band unit. The method900 demonstrates features for identifying coordinated multipointcommunication or an alternate mode for downlink data traffic to a UE.The identification includes assessment of network conditions along withproperties of the UE to receive the service. A non-transitory computerreadable storage medium can store specific instructions that, whenexecuted, cause some or all of the method 900 and/or some or all of anyother suitable method disclosed herein to be executed.

The method 900 may begin at block 902. At block 904, the coordinationdevice may receive channel state information for a user equipment. Thechannel state information may be received as part of a CSI reporttransmitted by the user equipment. The channel state information mayinclude channel quality indicators for one or more channels available tothe UE. The channel state information may include precoding informationsuch as a preferred beamforming matrix for pre-processing signals to betransmitted to the UE. The channel state information may include channelrank information for the channels available to the UE, the desiredmodulation and coding selection (MCS), and associated active set. Thechannel rank may indicate a number of spatial layers/channels availablefor communications with the UE.

At block 906, the coordination device may detect additional networksystem information. In some implementations, the additional networksystem information may include a characteristic of the UE. Thecharacteristic of the UE may be received concurrently or separately fromthe channel state information. Characteristics of the UE which may bereceived include application(s) executing on the UE which may requirethe downlink data traffic, communication protocol or data protocol theUE intends to use for the downlink data traffic (e.g., HTTPS, FTP, IMS,VoIP, MPEG-DASH, etc.), mobility of the UE (e.g., Doppler data or othermotion estimation), device type, operating system, antenna capabilities(e.g., number of receive antenna), power class or quality of serviceindicators such as delay and throughput specification. The additionalnetwork system information may include a characteristic of the RRUcurrently serving the UE. For example, the number of UEs currently beingserved by the RRU may be used to determine a load within the servicearea of the RRU. The additional network system information may includecharacteristics of other UEs. Characteristics of multiple UEs or RRUsmay be aggregated to generate a metric for the network. For example, anaverage signal-to-noise ratio may be generated for a sampling of UEs.

At block 908, the coordination device may determine whether dynamicthresholds are used. The determination may be based on a configurationvalue accessible by the coordination device. In some implementations,the configuration value may indicate whether or not dynamic thresholdsshould be generated. In some implementations, the configuration valuemay be implemented as a look up table identifying different thresholdtechniques based on, for example, UE characteristics, channel stateinformation, time, date, network conditions, etc. If the determinationat block 908 is affirmative, at block 910, the coordination device maygenerate selection thresholds for selecting downlink traffic mode forthe UE. The generation may be based on an average mobility of UEs withinthe network or within a service area of the RRU. The generation may bebased on maximum or mean Eigen-value of channel matrices of UEs withinthe network. The generation may be based on a total number of antennaswithin the network. In MIMO systems, the number of antennas availablemay be much greater than the number of RRUs because each RRU may includemultiple antennas.

Returning to block 908, if the coordination device determines thatthresholds will not be dynamically generated, at block 912, staticselection thresholds are obtained. The static selection thresholds maybe obtained from a memory or other configuration data store accessibleby the coordination device.

At block 914, using either the dynamic thresholds or static thresholds,the coordination device may identify a downlink data transmission modefor the UE. The assessment may compare one or more of the thresholds tospecific values for the UE or network to identify a mode. The comparisonmay be specified in a memory or other configuration data storeaccessible by the coordination device. For example, the modes may beselected using a truth table whereby satisfaction of certain conditionscause selection of a specific mode. Table 1 provides an example of sucha truth table. The truth table may be organized in priority such thatthe mode corresponding to the first set of conditions met will be used.

TABLE 1 Option Condition Mode 1 UE Mobility < mobility thresholdCoordinated --AND-- multipoint UE DL Channel Matrix Eigen-value Spread <matrix threshold 2 UE Mobility > mobility threshold Macro --OR--diversity UE channel matrix Eigen spread < matrix threshold --OR-- UEcount − TX Antenna Count > density threshold 3 Macro diversity == TRUEBest Server --AND - Mode Best effort traffic 4 True (default mode)Coordinated multipoint

In some implementations, the truth table may be generated using machinelearning. For example, observed characteristics of the network and/or UEmay be provided as inputs to a neural network trained using historicalactive set/mode decisions. The neural network may provide an outputvector of including one or more values indicating a predicted activeset, transmission mode, or transmission parameters (e.g., time,frequency, power, beamforming matrix, tone allocation, or channel rank.

At block 920, the coordination device may select the serving nodes toprovide transmission service according to the transmission modeidentified at block 914.

The coordination device may perform the selection at block 920 using thenetwork system information detected at block 906. In someimplementations, the UE may identify a neighbor active set of servingnodes. The neighbor active set of serving nodes may include nodes whichthe UE can detect (e.g., receive transmissions from). The selection mayconsider any serving nodes currently assigned to the UE along with theneighboring nodes. The coordination device may consider the load for thenodes, current and anticipated location of the UE in comparison to thenodes, or other detectable information. Serving nodes may be selectedbased on one or more of: (1) the link quality to one or more TRPs in thecurrent active set deteriorates below a threshold; (2) there is one ormore new TRPs where the link quality exceed a threshold; or (3) aredirection command is received from the network to redirect the UE suchas to distribute load to a more balanced allocation across the network.

As part of the selection, the coordination device may also identifyscheduling information for the serving nodes. The scheduling informationmay be selected to reduce interference between downlink transmissions tothe UE and other downlink transmissions. The interference reduction maybe achieved by adjusting the one or more of transmission mode, time,frequency, power, beamforming matrix, tone allocation, channel rank, ordirection of the transmission relative to other transmissions from theserving node or other serving nodes in proximity to a selected servingnode.

At block 922, the coordination device may configure the network for theselected downlink transmission mode. The configuration of the networkmay include adjusting one or more transceivers at the UE or the RRU. Theconfiguration may also include causing the UE to switch signalprocessing pipeline for received data transmissions (e.g., enablecoordinated multipoint decoding and disable coherent/non-coherentcombining). In some implementations, the configuration may includetransmitting a physical downlink control channel (PDCCH) messageincluding at least a portion of the configuration information. Theconfiguration information (e.g., active set and/or transmission mode),may be provided to the UE via another control channel message, radioresource control signaling, mobility management protocol, appended toidentifiers of the RRUs/TRPs in the active set, or other messaging fromthe coordination device to the UE.

Having achieved a configuration of the network suited to the networkconditions and UE conditions, the method 900 may end at block 990.However, the UE may be configured to periodically or aperiodicallyprovide channel state information reports. The coordination device mayrepeat the method 900 to assess updated reports. In someimplementations, the coordination device may identify a differencebetween an updated report and a previous report. If the difference doesnot meet a threshold, the method 900 may not expend the resources tore-assess the downlink traffic configuration for the UE.

The method 900 describes how a network device (e.g., BBU) may direct thedownlink traffic configuration for a UE.

FIG. 10 is a flow diagram illustrating an example method of dynamicallyconfiguring downlink data traffic modes for a user equipment in anetwork from the UE's perspective. The method 1000 may be performed inwhole or in part under control of a coordination device such as a UE.The method 1-00 demonstrates features for identifying coordinatedmultipoint communication or an alternate mode for downlink data trafficto a UE. The identification includes providing accurate and updatedreports of characteristics of the UE to the BBU and adjusting the UEbased on an identified downlink traffic mode.

The method 1000 may begin at block 1002. At block 1004, the coordinationdevice may receive a first active set including one or more servingnodes to provide downlink data transmission service in a first mode to aUE. The first active set and identifier for the first mode may bereceived from one or more TRPs serving the UE. The first active setand/or the first mode may be identified by a BBU controlling the RRU.The first active set and/or the first mode may be identified by the BBUusing the method 900.

At block 1006, the coordination device may detect a characteristic ofthe UE. The characteristic of the UE may include channel stateinformation. The channel state information may include channel qualityindicators for one or more channels available to the UE. The channelstate information may include precoding information such as a preferredchannel matrix for processing signals received from an antenna of theUE. The channel state information may include a channel rank. Additionalor alternative characteristics of the UE which may be received includeapplication(s) executing on the UE which may require the downlink datatraffic, communication protocol or data protocol the UE intends to usefor the downlink data traffic (e.g., HTTPS, FTP, IMS, VoIP, MPEG-DASH,etc.), mobility of the UE (e.g., Doppler data or other motionestimation), device type, operating system, antenna capabilities (e.g.,number of receive antenna), power class, or quality of service.

At block 1014, the coordination device may transmit the channel stateinformation and the characteristic to a BBU (e.g., base station). Thechannel state information may be provided using a channel stateinformation report. The additional characteristic(s) may be provided asa part of the report or via a separate message transmitted by thecoordination device.

At block 1015, the coordination device may receive a second active setof one or more serving nodes to provide the downlink data transmissionservice in a second mode. At this point in the method 1000, the UE isbeing asked to switch modes from the first mode to a second mode. Thecoordination device may first determine which mode is to be used fordownlink data traffic based on the received message and then adjustaccordingly.

At block 1016, the coordination device may determine whether the secondtransmission mode is CoMP. The determination at block 1016 may includecomparing a transmission mode identifier included in a message receivedfrom an RRU to a predetermined value associated with CoMP. If thedetermination at block 1016 is negative, at block 1018, the coordinationdevice may configure (e.g., adjust) the user equipment for macrodiversity downlink data transmissions. If the determination at block1016 is affirmative, at block 1010, the coordination device mayconfigure (e.g., adjust) the user equipment for coordinated multipointdownlink data transmissions.

After configuring the UE for the selected downlink data traffic mode, atblock 1022, the coordination device may determine whether the UE isstill actively using the downlink channel. The determination may bebased on receipt or transmission a message to or from the UE. Thedetermination may be based on execution status of an application or theoperating system. For example, the operating system of the UE mayinclude an airplane mode or a mode whereby all wireless communicationsare turned off. The determination may be based on a power state for theUE (e.g., powering down). If the UE is no longer active, the method 1000may end at block 1090. If the UE is still active, the method 1000 mayreturn to block 1006 to detect and transmit updated characteristics tothereby receive additional downlink transmission configurationinformation selected based on the updated characteristics.

User Equipment Assisted Communication Mode Determination

User equipment can determine a desired mode in which to receive adownlink data transmission. The desired mode can be either CoMP mode orthe alternative downlink data transmission mode. Then the user equipmentcan send a request to a network system, such as a base station, toprovide the downlink data transmission in the desired mode. The requestcan include desired active set data that identifies a desired active setof one or more serving nodes associated with the desired mode. Therequest can include an identifier for a desired transmission mode. Theidentifier may be a mode select bit included in the request, a messagetransmitted by the UE, or a value appended to one or more of theidentifiers of the desired active set of one or more serving nodes. Thenetwork system can determine a mode of downlink data transmission to theuser equipment based on the request and other data. This can contributeto the operation of a high data rate and high reliability wirelessnetwork.

The user equipment can determine the desired mode for all antennas ofthe user equipment. In some instances, the desired mode can bedetermined for a particular antenna or subset of antennas of the userequipment. Accordingly, in certain instances, a subset of antennas of auser equipment can receive first user data in CoMP mode and a differentsubset of the antennas of the same user equipment can receive seconduser data in the alternative downlink data transmission mode.

The user equipment can determine the desired mode of operation based onany suitable information available to the user equipment, such as anysuitable information disclosed herein associated with modedetermination. Such information can include, for example, mobility data,a network to user equipment channel matrix condition, inference data,metrics or other data associated with serving nodes of a current activeset, metrics or other data associated with neighbor nodes, the like, orany suitable combination thereof. Examples of metrics or other dataassociated with nodes include received signal strength indicator,signal-to-noise ratio estimate, or error rate statistics. Accordingly,based on information available to the UE, a request can be generated bythe UE to receive data in a desired mode of operation.

The request to operate in the desired mode can include information toindicate that the user equipment would like to change from one mode toanother. For example, the request can include information indicating totoggle between receiving data in the CoMP mode and the alternativedownlink data mode. In some instances, active set data of the requestcan indicate to operate in the same mode with a different set of servingnode(s). As one example, the request can indicate to continue receivingdata in CoMP mode from a different set of serving nodes than the currentactive set. As another example, the request can indicate to continuereceiving data in the alternative downlink data mode from a differentset of serving node(s) than the current active set.

FIG. 11 illustrates representative communications and events in aheterogeneous MIMO network 1100 associated with a user equipment 1100requesting to receive downlink data in a desired mode. Thecommunications and events of FIG. 11 are associated with the userequipment 1110, a remote radio unit (RRU) 1120, and/or a base band unit(BBU) 1130 of the heterogeneous MIMO network 1100. In the communicationsand events of FIG. 11, the UE 1110 selects a desired mode to receive adownlink data transmission and the BBU 1130 generates a downlinkschedule to schedule downlink data transmissions from one or moreserving nodes to the UE 1110.

In event 1150 of FIG. 11, the UE 1110 detects conditions. The UE 1110can gather any suitable information from which to determine a desiredmode to receive a downlink data transmission. The UE 1110 can detect anysuitable information disclosed herein for mode determination. The UE1110 selects a desired mode of receiving downlink data transmissionsbased on the gathered information. This determination can be based onany suitable principles and advantages disclosed herein.

The UE 1110 stores and updates an active set of one or more servingnodes that provide wireless transmission services to the UE 1110. Activeset data is provided by a network system that includes the RRU 1120 andthe BBU 1130. The UE 1110 also stores and updates a neighbor set of oneor more serving nodes that are available to provide wirelesstransmission services to the UE 1110 and are not included in the activeset. The UE 1110 may also store scheduling information such as thetransmission mode or other parameters for transmissions to or from theUE 1110.

The UE 1110 generates a requested downlink schedule at event 1152. Therequested downlink schedule includes desired active set data identifyingone or more serving nodes from which the UE 1110 requests to receivedownlink wireless transmission services. The desired active set data caninclude one or more serving nodes from the active set and/or one or moreserving nodes from the neighbor set. The desired active set data isbased on the determination of the desired mode by the UE 1110. Theschedule may include information identifying a desired transmissionmode.

In event 1154, the UE 1110 and the RRU 1120 establish a wirelessconnection. This can include providing a UE identifier and a requesteddownlink schedule. The RRU 1120 and the BBU 1130 communicate at event1156. The downlink schedule is provided from the RRU 1120 to the BBU1130. The RRU 1120 can also provide a UE identifier and an RRUidentifier to the BBU 1130.

The BBU 1130 includes a scheduler that generates a downlink schedule atevent 1158. BBU 1130 can receive information from a plurality of UEs andtake into account more information than available to a single UE indetermining the downlink data transmission mode to the UE 1110.Accordingly, it can be advantageous for a network system to determinethe downlink data transmission mode to the UE 1110 even if the UE 1110requests to receive downlink data in a particular mode. The networksystem may additionally or alternatively identify an active set ofservice nodes for data transmissions for the UE 1110.

The serving node schedule can be determined based on a request from theUE 1110 to receive downlink data in a desired mode and additionalnetwork system information. The additional network system informationcan include, for example, one or more of system load information such asload information for coordinated multipoint resources, data indicating amobility state of the UE 1110, a spatial channel condition of a channelassociated with the UE 1110, one or more characteristics of the UE 1110(e.g., an application type to utilize the transmission service, aprotocol to utilize over the transmission service, or a device type forthe UE 1110), one or more characteristics of one or more UEs other thanthe UE 1110, one or more conditions of one or more UEs other than the UE1110, one or more behaviors of one or more UEs other than the UE 1110,the like, or any suitable combination thereof.

Based on the request and the additional network system information, thescheduler of the BBU 1130 can (1) grant the request, (2) continue toschedule downlink data transmission to the UE 1110 without changing themode of operation or the active set for the UE 1110, or (3) cause theway the UE 1110 is being served to change in a way that is differentthan requested by the UE 1110.

The request can be granted when the additional network systeminformation is consistent with providing downlink data transmission tothe UE 1110 in the desired mode. To grant the request, the scheduler canupdate the active set for the UE 1110 to match the desired active set inthe request. Then the scheduler can cause downlink data transmission tothe UE 1110 in the desired mode from the one or more serving nodes ofthe desired active set.

In some instances, the additional network system information canindicate that the active set and current mode of operation can providebetter overall network services than granting the request. Accordingly,in such instances, the scheduler can continue to route downlink data tothe UE 1110 without changing the mode of operation or the active set forthe UE 1110.

The scheduler can cause the way the UE 1110 is being served to changedifferently than requested by the UE 1110 based on the request and theadditional network system information. For example, the scheduler candetermine to update the active set for the UE 1110 in a different waythan requested by the UE based on the request and the additional networksystem information. According to some other instances, the scheduler cancause a power level of a downlink data transmission to the UE 1110 to beadjusted based on the request and the additional network information.Any other parameter of the transmission from the network system, such asfrequency and/or time, can be similarly adjusted.

Referring back to FIG. 11, the BBU 1130 can provide downlink schedulingparameters to the RRU 1120 in event 1160. This can include providingupdated active set data for the UE 1110. Any other suitable schedulinginformation can be provided to the RRU 1120. In some instances wheredownlink scheduling parameters are unchanged, a confirmation that thedownlink scheduling parameters are unchanged and be sent in place of thedownlink scheduling parameters. Although FIG. 11 illustrates the sameRRU 1120 receiving a request downlink schedule from the UE 1110 andproviding a downlink schedule to the UE 1110, different RRUs canfacilitate communication between the UE 1110 and the BBU 1130 fordifferent communications as suitable.

As shown in FIG. 11, the RRU 1120 can provide downlink parameters to theUE 1110 in event 1162. This can include providing the UE 1110 withupdated active set data and/or one or more other parameters to configurethe UE 1110 for receiving downlink data from the network based on thedownlink data transmission schedule determined by the scheduler. In someinstances where downlink UE parameters are unchanged, a confirmationthat the downlink UE parameters are unchanged and be sent in place ofthe downlink UE parameters.

The UE 1110 can adjust a receiver of the UE 1110 for receiving data forthe selected downlink transmission mode in event 1164. The receiver ofthe UE 1110 can be adjusted for processing downlink data received in theselected mode from one or more serving nodes in the active set providedby the network system. The receiver of the UE 1110 can be adjusted forreceiving signals having a different power, direction, timing,frequency, or any suitable combination thereof. This can involveadjusting any suitable circuitry of the receiver. The receiver of the UE1110 can be included in a transceiver.

In event 1166, a transmitter of the RRU 1120 can be adjusted fortransmitting downlink data in the selected mode to the UE 1110. This caninvolve adjusting one or more of a transmission power, direction,timing, or frequency of a downlink data transmission from the RRU 1120.Adjusting the transmitter can involve adjusting any suitable circuitryof the transmitter. The transmitter can be included in a transceiver ofthe RRU 1120.

The UE 1110 and the RRU 1120 wirelessly exchange downlink data anduplink data in event 1168. During this exchange of data, the UE 1110 canprovide updated data to the BBU 1130 including an updated requesteddownlink schedule request and additional data associated with the UEfrom which to determine the selected mode of downlink data transmission.Accordingly, the scheduler of the BBU 1130 can dynamically select themode of downlink data traffic in the heterogeneous MIMO network 1100.

As discussed above, a variety of different UEs can wirelesslycommunicate with serving nodes in a heterogeneous MIMO network. Asexample UE will be discussed with reference to FIG. 12.

FIG. 12 is a schematic block diagram of an example UE 1200 according toan embodiment. The UE 1200 is configured for wirelessly communicatingwith a base station in a heterogeneous MIMO network. As illustrated, theUE 1200 includes a processor 1240, a user interface 1245, a data store1250, a beamformer 1255, antennas 1262 and 1264, a transceiver 1265, amotion detector 1270, a signal quality analyzer 1275, and an active setselector 1280. Some other UEs can include additional elements and/or asubset of the elements illustrated in FIG. 12.

The UE 1200 includes a plurality of antennas 1262 and 1264. Any suitablenumber of antennas can be included for wireless communication in CoMPmode and/or the alternative downlink data transmission mode. The UE 1200can include one or more arrays of antennas. A radio frequency (RF) frontend 1260 can process RF signals received via the antennas 1262 and 1264.The RF front end can also provide RF signals to the antennas 1262 and1264 for transmission. The transceiver 1265 includes a transmitter and areceiver. The transceiver 1265 can provide processing for transmittingand receiving RF signals associated with the antennas 1262 and 1264.

The processor 1240 is in communication with the transceiver 1265. Theprocessor 1240 is implemented by physical hardware arranged to performspecific operations to implement functionality related to determining adesired mode and causing a request related to the desired mode to betransmitted from the UE 1200. The processor 1240 can determine a desiredmode in which to receive downlink data and generated a request toreceive downlink data in the desired mode in accordance with anysuitable principles and advantages disclosed herein. The processor 1240can cause active set and neighbor set data to be stored and updated. Theprocessor 1240 can perform any other suitable processing for the UE1200.

The processor 1240 can be in communication with the motion detector 1270and the signal quality analyzer 1275. Accordingly, the processor 1240can receive and process information associated with conditions of the UE1200. The motion detector 1270 can include any suitable hardwarearranged to detect mobility information associated with the UE 1200. Thesignal quality analyzer 1275 can analyze the quality of signals receivedand/or transmitted by the antennas 1262 and 1264. This can provideinformation associated with a spatial channel condition of the UE 1200.The information associated with conditions of the UE 1200 can beprovided to the processor 1240 for determining a desired mode in whichto receive downlink data. In some instances, some or all of thefunctionality of the motion detector 1270 and/or the signal qualityanalyzer can be implemented by the processor 1240.

The active set selector 1280 can identify a desired active set of one ormore serving nodes associated with the desired mode determined by theprocessor 1240. The active set selector 1280 can select the desiredactive set based on data associated with one or more of: one or moreserving nodes in the active set, one or more serving nodes in theneighbor set, mobility data associated with the UE 1200, a spatialchannel condition associated with the UE 1200, or one or morecharacteristics of the UE 1200. Desired active set data can be providedwith the request to operate in the desired mode. The active set selector1280 can be implemented by dedicated circuitry and/or circuitry of theprocessor 1240.

The beamformer 1255 can perform any suitable beamforming functionalityfor the UE 1200. The beamformer 1255 can set and/or adjust one or moreparameters associated with receiving and/or transmitting signalsassociated with the antennas 1262 and 1264 of the UE 1200. Thebeamformer 1255 can be implemented by dedicated circuitry and/orcircuitry of the processor 1240.

The UE 1240 includes a data store 1250. The data store 1250 can storeinstructions that can be executed by the processor 1240 to implement thefeatures described. The data store 1250 can store active set data andneighbor set data for the UE 1200. The data store 1250 can store anyother suitable data for the UE 1200. The data store 1250 can include anysuitable memory elements arranged to store data.

Several elements included in the UE 1200 may be coupled by a bus 1290.The bus 1290 can be a data bus, communication bus, other bus, or anysuitable combination thereof to enable the various components of the UE1200 to exchange information.

As illustrated, the UE 1200 also includes a user interface 1245. Theuser interface 1245 can be any suitable user interface, such as adisplay and/or an audio component. In some instances, the user interface1245 can include one or more of touch screen capabilities, a button, aknob, a switch, or a slider.

FIG. 13 is a flow diagram of an example process 1300 of requesting aselected communication mode in which to receive data at an antenna of aUE according to an embodiment. The process 1300 can be performed by anysuitable UE, such as any suitable UE disclosed herein. The process 1300illustrates aspects of a UE generating and sending a request to receivedownlink data in a desired mode of operation. The process 1300 can beperformed in each of a plurality of UEs that are concurrently wirelesslycommunicating with the same base station.

The process 1300 begins at block 1302. At block 1304, active set datatransmitted from a base station is received by a UE. The active set dataidentifies a set of one or more serving nodes to provide downlink datato the UE. The UE stores the active set data and updates the active setdata in response to receiving updated active set data from the basestation. The active set data can be received by the processor 1240 andstored in the data store 1250 of the UE 1200 of FIG. 12, for example.

The UE detects conditions at block 1306. Detecting conditions associatedwith the UE can provide useful information from which the UE generates arequest to receive downlink data in a selected mode. The detectedconditions can include any suitable conditions and/or metrics disclosedherein. For example, the UE can detect a mobility state of the UE and/ora spatial channel condition of the UE. One or more conditions can bedetected using the motion detector 1270 and/or the signal qualityanalyzer 1275 of the UE 1200, for example.

The UE determines a selected mode of wirelessly receiving data using anantenna element. The selected mode is either a coordinated multipointmode or an alternate downlink data transmission mode. The selected modecan be determined in accordance with any suitable principles andadvantages disclosed herein. A processor, such as the processor 1240 ofthe UE 1200, can be used to determine the selected mode. The selectedmode can be for some or all of the antennas of the UE. At decision block1308, the UE can determine whether conditions are suitable for CoMP. Ifconditions are suitable for CoMP mode, CoMP mode is selected as thedesired mode at block 1310. Alternatively, if one or more conditions areunsuitable for CoMP mode, an alternative downlink data transmission modeis selected as the desired mode at block 1312. The alternative downlinkdata transmission mode can be any suitable alternative downlink datatransmission mode disclosed herein.

The determination of the selected mode can be based on the conditionsdetected at block 1306. For instance, the selected mode can bedetermined based on a mobility state of the UE and/or a spatial channelcondition of the UE. A threshold level of the mobility state associatedwith operating in the CoMP mode can be determined based on theconditions detected at block 1306. Alternatively or additionally, athreshold level of the spatial channel state condition associated withoperating in the CoMP mode can be determined based on the conditionsdetected at block 1306.

In some implementations, the UE may additionally or alternativelyidentify a desired active set of serving nodes for wirelessly receivingdata. The desired serving nodes may be identified based on theconditions detected at block 1306. For example, the UE may detect asignal from a TRP and based on received-signal-strength or other metricfor one or more signals from the TRP, determine the quality fortransmissions received from the TRP.

At block 1314, the UE can send a request via at least one antenna toreceive data in the selected mode. The processor of the UE can cause thetransmission via at least one antenna of the UE. For instance, in the UE1200, the processor 1240 can cause transmission of the request usingantenna 1262. The request can include a desired active set. The requestcan include information identifying the selected mode, such as one ormore mode select bits. The process ends at block 1316.

Some or all of the process 1300 can be performed repeatedly while the UEis active. Accordingly, the UE can provide requests to receive data in adesired mode based on up to date conditions detected by the UE. Therequest can be updated periodically and/or dynamically. As one example,a UE can be located in a crowded football stadium and request to receivedata in the CoMP data transmission mode because of, for instance, ahigher number of TRPs that are likely available in the stadium. Afterthe UE leaves the football stadium and is located in a residential area,the UE can request to receive data in an alternative downlink modebecause the TRPs may be more sparsely distributed in the residentialarea than in the stadium. As another example, the UE can receive data inthe CoMP mode while the UE has relatively low mobility. In response to asignificant increase in mobility, such as being located in a vehicle ona highway, the UE can request to receive data in the alternativedownlink data transmission mode.

FIG. 14 is a flow diagram of an example process 1400 of controlling adownlink data transmission mode to a UE based on a request from the UEaccording to an embodiment. The process 1400 can be performed by anysuitable network system, such as any suitable base station. Forinstance, some or all of the process 1400 can be performed by thebaseband unit 510 of FIG. 5 and/or the baseband unit 820 of FIG. 8. Theprocess 1400 illustrates aspects of a network system determining adownlink data transmission mode based on a request from a UE to receivedata in particular mode and additional network system information.

The process 1400 begins at block 1402. At block 1404, a scheduler of thenetwork system receives network system information. The network systeminformation can be received via one or more antennas of a base station.The network system information can be received from a plurality of UEs.Accordingly, the scheduler can have access to additional data that isunavailable to a UE requesting to receive downlink date in theparticular mode. The network system information can include any suitableinformation from which a network scheduler determines a mode of downlinkdata transmission to a UE disclosed herein. The network systeminformation can include mobility state information for one or more UEs,spatial channel state conditions for one or more UEs, system loadinformation, characteristics of one or more UEs, the like, or anysuitable combination thereof. The scheduler receives a request from a UEto receive downlink data in a particular mode at block 1406. The requestcan include desired active set data and/or a one or more mode selectbits.

Based on the request and additional network system information, thescheduler determines a downlink data transmission mode for wirelesslytransmitting data to a UE. The scheduler can also determine the activeset for a UE and/or a subset of antennas of a UE. The determineddownlink data transmission mode is either CoMP mode or an alternativedownlink data transmission mode. The alternative downlink datatransmission mode is a non-CoMP mode. The alternative downlink datatransmission mode can be, for example, synchronized transmission acrossmultiple network nodes for coherent combining, transmissions acrossmultiple network nodes for non-coherent combining, or individualtransmission from a selected best serving node.

Referring to FIG. 14, at decision block 1408, the scheduler determineswhether to grant the request. The request can be granted or denied basedon any suitable information and/or methods disclosed herein. If therequest is granted at block 1408, the particular mode identified in therequest is set as the downlink data transmission mode to the UE at block1410. Alternatively, if the request is denied at block 1408, thescheduler can determine whether to adjust a downlink data transmissionparameter based on the request at decision block 1412. In response todetermining to adjust the downlink data parameter at block 1412, thescheduler can cause a downlink data transmission parameter to beadjusted at block 1414. One or more of the following downlink datatransmission parameters can be adjusted: power, time, frequency, ordirection. Alternatively or additionally, active set data can beadjusted without granting the request.

At block 1416, active set data is transmitted to the UE. The active setdata can include any suitable data that identifies an active set. Theactive set data can identify the active set for the UE. In someinstances, the active set data can identify changes to the active setfor the UE. According to certain instances, the active set data canindicate that the active set for the UE is unchanged. In response to theparticular mode being set as the downlink data transmission mode atblock 1410, the active set data transmitted at block 1416 can identifythe desired active set provided by the UE as the active set for the UE.In response to the request being denied at block 1408 and thedetermination not to adjust downlink data transmission at block 1412,the active set data transmitted at block 1416 can indicate that theactive set is unchanged. In response to the request being denied atblock 1408 and the determination to adjust downlink data transmission atblock 1412, the active set data transmitted at block 1416 can indicatethat the active set is unchanged in some instances and a change to theactive set in some other instances.

At block 1418, downlink data is transmitted to the UE in the downlinkdata transmission mode determined based on the request and additionalnetwork system information. The UE receives the downlink data from theone or more serving nodes in the active set.

Some or all of the process 1400 can be performed repeatedly.Accordingly, the scheduler can set the downlink data transmission modeto the UE based on an up to date request and up to date network systemdata. The process 1400 can be performed for each UE in communicationwith a network system. The process 1400 can be performed for two or moredifferent subsets of one or more antennas of the same UE.

Further Embodiments

Additional embodiments are described with reference to FIGS. 15 to 16B.These figures illustrate examples of a heterogeneous MIMO networkserving UEs in different modes with active set allocation.

FIG. 15 is a diagram illustrating allocation of active sets andtransmission modes in a heterogeneous MIMO environment 1500. This figureillustrates that different UEs can be served in different downlink datatransmission modes. As illustrated, the heterogeneous MIMO environment1500 includes four RRUs 1502, 1504, 1506, and 1508 and three UEs 1512,1514, and 1516.

The first UE 1512 is static. Thus, the first UE 1512 has low mobility.The first UE 1512 is also near several RRUs 1502, 1504, and 1506.Accordingly, a network system can schedule downlink data transmissionsto the first UE 1512 in CoMP mode. The network system can identify RRUs1502, 1504, and 1506 as the active set of serving nodes for the first UE1502 in the CoMP mode.

The second UE 1514 is near a single RRU 1508. Without multiple servingnodes available, the network system can schedule downlink datatransmissions to the second UE 1514 in an alternative downlink datatransmission mode, such as best server mode (e.g., best server selectionSIMO, best server selection SU-MIMO, best server selection MU-MIMO). Thenetwork system can identify RRU 1508 as the active set for the second UE1508 in the best server mode.

The third UE 1516 is moving at 30 kilometers per hour. Thus, the thirdUE 1516 has relatively high mobility. The first UE 1515 is also nearRRUs 1502 and 1504. With relatively high mobility and more than oneserving node available, the network system can schedule downlink datatransmissions to the third UE 1516 in an alternative downlink datatransmission mode, such as SFN mode. The network system can identifyRRUs 1502 and 1504 as the active set of serving nodes for the third UE1506 in the SFN mode.

FIGS. 16A and 16B are diagrams illustrating different allocations ofactive sets and transmission modes in a heterogeneous MIMO environment1600 with dynamic network demands. These figures illustrate that theactive set and/or downlink data transmission mode can change due tochanging network conditions in a heterogeneous MIMO environment. Forinstance, the active set and downlink data transmission mode can changeas a function of active UEs in the heterogeneous MIMO environment 1600.FIGS. 16A and 16B provide an example in which an active set for a UE canbe determined based on network information associated with one or moreother UEs.

In FIG. 16A, there is a single UE 1612 in the heterogeneous MIMOenvironment 1600. As illustrated, the network can schedule downlink datato the UE 1612 in a best server mode with an active set of RRU 1606. TheRRUs 1602, 1604, and 1608 can be unused in this case.

Additional UEs can enter the heterogeneous MIMO environment 1600. Asshown in FIG. 16B, two additional active UEs 1614 and 1616 are presentin the heterogeneous MIMO environment 1600 relative to FIG. 16A. The UEs1614 and 1616 are both relatively close to the UE 1612 and the RRU 1606.The network can schedule downlink data to each of the UEs 1612, 1614,and 1616 in CoMP mode an active set of RRUs 1602, 1604, and 1608. InFIG. 16A, the active set for the UE 1612 included RRU 1606. However,upon assessment of the changing network conditions (e.g., the additionalpresence of UE 1614 and UE 1616 and associated wireless communicationdesires of these UEs), the environment 1600 may be reconfigured toallocate the resources to serve the UE 1612, the UE 1614, and the UE1616. The reconfiguration may include assigning a new active set of oneor more serving nodes such as for UE 1612. Alternatively oradditionally, the reconfiguration can include changing a downlink datatransmission mode such as for UE 1612 from BSM in FIG. 16A to CoMP inFIG. 16B. The configuration in FIG. 16B can provide improved spatialchannel conditions relative to the case where RRU 1606 alone is used toseparate beams for three concurrent UEs.

Although the embodiments discussed herein provide various example ofoperating in the CoMP mode or an alternative downlink data transmissionmode, there are numerous use cases where one or another is preferred.Some additional examples will briefly be discussed.

CoMP mode can be preferred for high definition video streaming. CoMPmode can be preferred for downlink data transmission associated withvirtual and/or augmented reality. CoMP mode can be preferred forrelatively large file transfers. When a UE is in mobility, best servermode can be preferred for high definition video streaming, virtualand/or augmented reality data, and relatively large file transfers.

A soft combining mode can be preferred for relatively low latency highquality audio. Soft combining mode can be preferred for voice callingand video telephony.

A non-coherent combining mode can be preferred for relatively lowlatency robotic control. For industrial automation control, anon-coherent combining mode can be preferred. Advanced driver assistancesystems (ADAS) can prefer a non-coherent combining mode.

Terminology, Applications, and Conclusion

Depending on the embodiment, certain acts, events, or functions of anyof the processes or algorithms described herein can be performed in adifferent sequence, can be added, merged, or left out altogether (e.g.,not all described operations or events are necessary for the practice ofthe algorithm). Moreover, in certain embodiments, operations, or eventscan be performed concurrently, e.g., through multi-threaded processing,interrupt processing, or multiple processors or processor cores or onother parallel architectures, rather than sequentially.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements, and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements, and/or steps are in any way required forone or more embodiments or that one or more embodiments necessarilyinclude logic for deciding, with or without other input or prompting,whether these features, elements, and/or steps are included or are to beperformed in any particular embodiment. The terms “comprising,”“including,” “having,” and the like are synonymous and are usedinclusively, in an open-ended fashion, and do not exclude additionalelements, features, acts, operations, and so forth. Additionally, thewords “herein,” “above,” “below,” and words of similar import, when usedin this application, shall refer to this application as a whole and notto any particular portions of this application. Where the contextpermits, words in the above Detailed Description of Certain Embodimentsusing the singular or plural may also include the plural or singular,respectively. Also, the term “or” is used in its inclusive sense (andnot in its exclusive sense) so that when used, for example, to connect alist of elements, the term “or” means one, some, or all of the elementsin the list.

Disjunctive language such as the phrase “at least one of X, Y, Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to present that an item, term, etc., may beeither X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z).Thus, such disjunctive language is not generally intended to, and shouldnot, imply that certain embodiments require at least one of X, at leastone of Y, or at least one of Z to each be present.

Unless otherwise explicitly stated, articles such as “a” or “an” shouldgenerally be interpreted to include one or more described items.Accordingly, phrases such as “a device configured to” are intended toinclude one or more recited devices. Such one or more recited devicescan also be collectively configured to carry out the stated recitations.For example, “a processor configured to carry out recitations A, B andC” can include a first processor configured to carry out recitation Aworking in conjunction with a second processor configured to carry outrecitations B and C.

The word “coupled,” as generally used herein, refers to two or moreelements that may be either directly coupled to each other, or coupledby way of one or more intermediate elements. Likewise, the word“connected,” as generally used herein, refers to two or more elementsthat may be either directly connected, or connected by way of one ormore intermediate elements.

As used herein, the terms “determine” or “determining” encompass a widevariety of actions. For example, “determining” may include calculating,computing, processing, deriving, generating, obtaining, looking up(e.g., looking up in a table, a database or another data structure),ascertaining and the like via a hardware element without userintervention. Also, “determining” may include receiving (e.g., receivinginformation), accessing (e.g., accessing data in a memory) and the likevia a hardware element without user intervention. Also, “determining”may include resolving, selecting, choosing, establishing, and the likevia a hardware element without user intervention.

As used herein, the terms “provide” or “providing” encompass a widevariety of actions. For example, “providing” may include storing a valuein a location of a storage device for subsequent retrieval, transmittinga value directly to the recipient via at least one wired or wirelesscommunication medium, transmitting or storing a reference to a value,and the like. “Providing” may also include encoding, decoding,encrypting, decrypting, validating, verifying, and the like via ahardware element.

As used herein, the term “message” encompasses a wide variety of formatsfor communicating (e.g., transmitting or receiving) information. Amessage may include a machine readable aggregation of information suchas an XML document, fixed field message, comma separated message, or thelike. A message may, in some implementations, include a signal utilizedto transmit one or more representations of the information. Whilerecited in the singular, it will be understood that a message may becomposed, transmitted, stored, received, etc. in multiple parts.

As used herein a “user interface” (also referred to as an interactiveuser interface, a graphical user interface or a UI) may refer to anetwork based interface including data fields and/or other controls forreceiving input signals or providing electronic information and/or forproviding information to the user in response to any received inputsignals. A UI may be implemented in whole or in part using technologiessuch as hyper-text mark-up language (HTML), Flash, Java, .net, webservices, and rich site summary (RSS). In some implementations, a UI maybe included in a stand-alone client (for example, thick client, fatclient) configured to communicate (e.g., send or receive data) inaccordance with one or more of the aspects described.

As used herein a “transmit-receive point” (TRP) (which can alternativelybe referred to as a transmission reception point) may refer to atransceiver device or one transceiver element included in a device. Whenincluded as a transceiver element, the device may include multiple TRPs.The TRP may include one or more antennas which are coupled to signalprocessing circuitry. The signal processing circuitry may be included inthe device. The TRP may include additional elements to facilitatetransmission or receipt of wireless signals for one or more UEs. Exampleof such elements may include a power source, amplifier,digital-to-analog converter, analog-to-digital converter, or the like.When a TRP is allocated, such as by a BBU, to provide service to a UE,the TRP may be said to be a “serving node” for the UE.

As used herein a “remote radio unit” (RRU) may refer to a device forcontrolling and coordinating transmission and receipt of wirelesssignals for one or more UEs. An RRU may include or be coupled with oneor more TRPs. The RRU may receive signals from the TRP and include thesignal processing circuitry. The signal processing circuitry may beselectively operated to facilitate processing of signals associated withdifferent TRPs.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it can beunderstood that various omissions, substitutions, and changes in theform and details of the devices or algorithms illustrated can be madewithout departing from the spirit of the disclosure. For example,circuit blocks and/or method blocks described herein may be deleted,moved, added, subdivided, combined, arranged in a different order,and/or modified. Each of these blocks may be implemented in a variety ofdifferent ways. Any portion of any of the methods disclosed herein canbe performed in association with specific instructions stored on anon-transitory computer readable storage medium being executed by one ormore processors. As can be recognized, certain embodiments describedherein can be embodied within a form that does not provide all of thefeatures and benefits set forth herein, as some features can be used orpracticed separately from others. The scope of certain embodimentsdisclosed herein is indicated by the appended claims rather than by theforegoing description. All changes which come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

What is claimed is:
 1. A network system comprising: antenna elements;and a scheduler in communication with the antenna elements, thescheduler configured to: receive, via at least one antenna elementincluded in the antenna elements, a request from a user equipment towirelessly receive data in a particular mode, wherein the particularmode is either a coordinated multipoint mode or an alternate downlinkdata transmission mode; based on the request and additional networksystem information, determine a downlink data transmission mode to theuser equipment and active set data so as to provide a wireless downlinktransmission service to the user equipment differently than identifiedin the request, wherein the active set data identifies one or moreserving nodes to provide the wireless downlink transmission service tothe user equipment in the downlink data transmission mode; and causetransmission of the active set data to the user equipment.
 2. Thenetwork system of claim 1, wherein the scheduler is configured to causetransmission of an indication of the downlink data mode to the userequipment.
 3. The network system of claim 1, wherein the requestidentifies a user equipment active set, and wherein the scheduler isconfigured to dynamically generate the active set data identifying theone or more serving nodes, and wherein the one or more serving nodesinclude a node that is included in the user equipment active set.
 4. Thenetwork system of claim 1, wherein the additional network systeminformation comprises load information for coordinated multipointresources.
 5. The network system of claim 1, wherein the additionalnetwork system information comprises a spatial channel condition of achannel associated with the user equipment.
 6. The network system ofclaim 1, wherein the additional network system information comprises acharacteristic of the user equipment, wherein the characteristiccomprises at least one of: an application type to utilize thetransmission service, a protocol to utilize over the transmissionservice, a mobility state of the user equipment, or a device type forthe user equipment.
 7. The network system of claim 1, wherein thescheduler is configured to cause downlink traffic to be routed to theuser equipment in the alternate downlink data transmission mode and tobe routed to a second user equipment in a coordinated multipoint mode.8. The network system of claim 1, wherein the alternate downlink datatransmission mode comprises at least one of: synchronized transmissionacross multiple network nodes for coherent combining, transmissionsacross multiple network nodes for non-coherent combining, or individualtransmission from a selected best serving node.
 9. The network system ofclaim 8, wherein the alternate downlink data transmission mode comprisesindividual transmission from the selected best serving mode, wherein thescheduler is configured to identify the selected best serving node, andwherein the one or more serving nodes include the selected best servingnode.
 10. The network system of claim 1, wherein the scheduler isconfigured to: based on the request and the additional network systeminformation, determine a transmission power for the one or more servingnodes; and transmit a control message to the one or more serving nodesto cause adjustment of a transmitter according to the transmissionpower.
 11. The network system of claim 1, wherein the wireless downlinktransmission service comprises at least one of: individual network nodetransmission, synchronized transmission across multiple network nodesfor coherent combining, transmissions across multiple network nodes fornon-coherent combining, and multiple transmissions for the userequipment to select.
 12. The network system of claim 1, wherein theadditional network information is unavailable to the user equipment. 13.The network system of claim 1, wherein the scheduler is configured toset the downlink data transmission mode to the particular mode inresponse to the additional network system information being consistentwith providing downlink data transmission to the user equipment in theparticular mode.
 14. The network system of claim 1, wherein theparticular mode is the coordinated multipoint mode and the downlink datatransmission mode to the user equipment is the alternate downlink datatransmission mode.
 15. A network system comprising: antenna elements;and a scheduler in communication with the antenna elements, thescheduler configured to: receive, via at least one antenna elementincluded in the antenna elements, a request from a user equipment towirelessly receive data in a particular mode, wherein the particularmode is either a coordinated multipoint mode or an alternate downlinkdata transmission mode, wherein the request identifies a user equipmentactive set; based on the request and additional network systeminformation, determine a downlink data transmission mode to the userequipment and active set data, wherein the active set data identifiesone or more serving nodes to provide a wireless downlink transmissionservice to the user equipment in the downlink data transmission mode;dynamically generate the active set data identifying the one or moreserving nodes to provide the wireless downlink transmission service tothe user equipment in the downlink data transmission mode, wherein theone or more serving nodes include a node that is not included in theuser equipment active set identified in the request; and causetransmission of the active set data to the user equipment.
 16. A methodof determining and implementing a downlink traffic mode to a userequipment, the method comprising: receiving, via at least one antennaelement, a request from a user equipment to wirelessly receive data in aparticular mode, wherein the particular mode is either a coordinatedmultipoint mode or an alternate downlink data transmission mode; basedon the request and additional network system information, determining adownlink data transmission mode for wirelessly transmitting data to theuser equipment and active set data so as to provide a wireless downlinktransmission service to the user equipment differently than identifiedin the request, wherein the active set data identifies one or moreserving nodes to provide the wireless downlink transmission service tothe user equipment in the downlink data transmission mode; andtransmitting the active set data to the user equipment.
 17. The methodof claim 16, further comprising transmitting an indication of thedownlink data transmission mode to the user equipment.
 18. The method ofclaim 16, wherein the request identifies a user equipment active set,and wherein the method further comprises dynamically generating theactive set data identifying the one or more serving nodes, and whereinthe one or more serving nodes includes a node that is not included inthe user equipment active set.
 19. The method of claim 16, wherein theadditional network system information comprises load information forcoordinated multipoint resources.
 20. The method of claim 16, whereinthe additional network system information comprises a spatial channelcondition of a channel associated with the user equipment.
 21. Themethod of claim 16, wherein the additional network system informationcomprises a characteristic of the user equipment, wherein thecharacteristic comprises at least one of: an application type to utilizethe transmission service, a protocol to utilize over the transmissionservice, a mobility state of the user equipment, or a device type forthe user equipment.
 22. The method of claim 16, further comprisingcausing downlink traffic to be routed to the user equipment in thealternate downlink data transmission mode and to be routed to a seconduser equipment in a coordinated multipoint mode, and wherein thealternate downlink data transmission mode comprises at least one of:synchronized transmission across multiple network nodes for coherentcombining, transmissions across multiple network nodes for non-coherentcombining, or individual transmission from a selected best serving node.23. The method of claim 16, further comprising: determining atransmission power for the one or more serving nodes based at least inpart on the request and the additional network system information; andtransmitting a control message to the one or more serving nodes to causeadjustment of a transmitter according to the transmission power.
 24. Themethod of claim 16, wherein the wireless downlink transmission servicecomprises at least one of: individual network node transmission,synchronized transmission across multiple network nodes for coherentcombining, transmissions across multiple network nodes for non-coherentcombining, or multiple transmissions for the user equipment to select.